In general, in case that the number of keys in a keypad for inputting data is small since a terminal is small-sized like a portable phone, various methods are being used in order to input characters. There is a ‘toggle’ method as a representative method, in which each numerical key from ‘0’ to ‘9’ is made to correspond to several character keys, so that a desired character is selected and inputted. Also, there is a ‘chun-ji-in’ (in which ‘chun(·)’ means the sky, ‘ji()’ means the earth, and ‘in()’ means the human in Korean) method for inputting a word by combination of one or more consonants and one or more vowels in which each consonant is assigned to each key and a vowel is produced by combination of ‘chun(·)’, ‘ji()’, and ‘in()’ according to a configurational principle of the vowel. There is also a ‘naragul’ (which means a mother language in Korean) method for inputting all consonants and vowels by using the minimum number of consonant keys and vowel keys and modifying them.
Since the ‘toggle’ method requires too many a number of times of manipulation when characters are inputted, to thus consume much time, methods for inputting characters with a smaller number of times of key manipulation have been developed as in the case of the ‘chun-ji-in’ method or the ‘naragul’ method. In particular, since the ‘chun-ji-in’ method or the ‘naragul’ method needs a relatively small number of times of key manipulation when characters are inputted, it has been employed in a number of terminals.
However, since complicated and burdensome key manipulations are needed in order to input characters by using keypads formed of ten numerical keys from ‘0’ to ‘9,’ characters cannot be speedily inputted.